Ink cartridges for “inkjet” printers typically contain one or more ink reservoirs, a means of supplying ink to a print head which contains a number of ink microchambers each having an orifice or nozzle, and electrical circuitry to control the operation of the nozzles. In a conventional configuration, ink from a reservoir is supplied through a porous element by capillary action or surface tension forces to a print head assembly composed of an array of ink microchambers. The print head typically includes an array of such ink microchambers with each ink microchamber including an ink ejection orifice or nozzle typically on the order of 4 to 6 microns in diameter. In operation, a minute droplet of ink is ejected from the orifice or nozzle in the direction of the paper or media to be printed, and an image is built up of a multitude of such minute droplets. Two methods are commonly used to eject the ink droplet from the orifice: heat displacement and mechanical displacement.
In the heat displacement method, an electrical resistor or heat element is positioned within the ink microchamber adjacent to the ink ejection orifice or nozzle. When electrical current is applied via the control circuit, the resistor temperature increases rapidly to a high temperature causing a vapor bubble to form in the microchamber which pushes ink from the orifice. When the bubbles bursts or collapses the ink droplet is ejected, and more ink is drawn into the ink microchamber by capillary action.
In the mechanical displacement method, a piezo-electric transducer within the ink microchamber is caused to expand by application of electrical current through the control circuit. When the transducer expands it mechanically ejects a droplet of ink from the microchamber orifice or nozzle. When the current is turned off, the piezo-electric transducer contacts drawing more ink into the ink microchamber.
Heretofore a problem has existed in refilling depleted ink cartridges in that the cleaning and recharging or refilling process often resulted in air bubbles being formed in the ink reservoirs and/or the fluid passage(s) to the print head(s) and/or in the ink microchambers of the print head array of the ink cartridge. Such air bubbles sometimes result in interruption of the flow of ink to the ink microchambers of the print head causing it to stop “printing.”
It is conventional in the ink cartridge recycling industry for the recharging process to include a centrifugation step. However, conventionally, the centrifugal force is applied to the cartridge in a direction opposite to the direction from which ink droplets are ejected from the orifices or nozzles of the print head. Typically the centrifugal force is applied so as to cause wash fluid to flow toward a port from which it may exit the cartridge. In many common cartridge designs, the print head and port or ports are located on opposite ends of the ink cartridge. In some cartridge designs the print head is located on one end of the cartridge and the port or ports may be located on the side of the generally cube or rectangular cylinder shaped ink cartridge. Further, there is variety in the design of the internal fluid passages for flow of ink from the reservoir to the print head of ink cartridges. These factors, alone and in combination, contribute to existence of the afore-mentioned “air lock” problem.
The present invention is directed to solving this “air lock” problem by introducing a centrifugation step in the cleaning, reconditioning and recharging or refilling process of a previously depleted ink cartridge body in which air is expelled from the region of the print head of the previously depleted ink cartridge. This is accomplished by centrifuging the cartridge containing a predetermined quantity of water or other ink miscible liquid for a predetermined time in an orientation with the print head facing radially outward or substantially away from the axis of rotation of the rotor to thus force the liquid from the reservoir through the cartridge ink channels to the microchamber arrays of the print head and thence out of the print head through the orifices or nozzles. In other words, the cartridge is oriented in the centrifuge so that during operation the liquid is accelerated through the cartridge in the same direction as is the ink flowing through the cartridge during normal printing operations. This technique results in air entrapped or entrained at any location between the ink reservoir and the microchamber arrays being purged by the liquid and exhausted via the nozzles as the liquid flows into the microchamber arrays and out through the ink ejection orifices or nozzles.
The second problem to which the present invention is directed is replacement of the cartridge cap. It is conventional in the ink cartridge recycling industry to remove the cartridge cap to gain access to the ink reservoirs for cleaning and recharging during a resealing process. Conventionally, the original cap is thereafter affixed to the ink cartridge by means of adhesive or glue. A primary drawback of this method is that there typically is a period of a few to several minutes for bonding to take place during which alignment must be maintained, which increases production time and cost. Further, resealing with adhesive often fuses the sections together, rendering subsequent separation for additional recharging cycles difficult or impossible. A further drawback of the conventional method is that adhesive is a consumable which adds to production costs and cost of the final product. The present invention is directed to solving these problems by providing a recharged and resealed ink cartridge and method of manufacture in which the ink cartridge cap and the ink cartridge body are joined in a matter of seconds rather than minutes without the use of consumable adhesives or glues.
A third drawback in both original equipment as well as conventionally recharged and resealed ink cartridges is that a particular manufacture's inkjet printer requires use of a specially “keyed” ink cartridge for installation into that manufacture's printers. The present invention provides a recharged and resealed ink cartridge with a keyless replacement cap which permits the resealed ink cartridge to be installed and used in a variety of different printers.